A known example of an optical scanning apparatus scans an object being illuminated by irradiating the object being illuminated with illumination light from an optical fiber through an illumination optical system. The scanning endoscope apparatus scans while displacing the emission end of the optical fiber with an actuator and deflecting the illumination light, detects backscattered light from the object being illuminated, and generates an image (for example, see JP 5190267 B2 (PTL 1)).
Before scanning a target area of the object being illuminated, the optical scanning apparatus disclosed in PTL 1 directly scans an optical position detector provided with a coordinate information acquisition function, such as a Position Sensitive Detector (PSD), with illumination light and acquires the scanning pattern of the illumination light. During scanning of a target area of the object being illuminated, the optical scanning apparatus uses the scanning pattern, acquired in advance, to calibrate the pixel positions in the image of the object being illuminated obtained by scanning the object being illuminated and generates a display image.